Practice worksheet for identifying DNA mutations and their impacts on protein sequences.

Let’s solve this step by step.

We are given a DNA sequence and asked to:
1. Transcribe it into mRNA (replace T with U, keep A, C, G as is — but remember: mRNA is complementary to the template strand).
2. Translate the mRNA into amino acids using the codon table.
3. Identify what kind of mutation occurred if any base changes.
4. Determine if the mutation affects the protein (silent, missense, nonsense, frameshift).

But wait — looking at the worksheet structure, we’re actually being given three different mutated versions of the original DNA sequence, and for each, we must fill in:

- The mutated DNA sequence
- The transcribed mRNA
- The translated amino acid chain
- Type of mutation
- Effect on protein

Also note: The original DNA sequence is labeled “Original DNA Sequence #1” and is:

> TAC ACC TTG GCG ACG ACT

This is likely the template strand, because transcription uses the template to make complementary mRNA.

So let’s start with the original to understand the baseline.

---

Step 1: Original DNA → mRNA → Protein

Original DNA (template):
TAC ACC TTG GCG ACG ACT

Transcribe to mRNA (complementary, replace T→U):
AUG UGG AAC CGC UGC UGA

Now translate using codon table:

- AUG = Methionine (Met) — START
- UGG = Tryptophan (Trp)
- AAC = Asparagine (Asn)
- CGC = Arginine (Arg)
- UGC = Cysteine (Cys)
- UGA = STOP

So original protein: Met - Trp - Asn - Arg - Cys - [STOP]

That’s 5 amino acids + stop.

---

Now let’s go through each mutated version.

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## Mutated DNA Sequence #1:

Given:
TAC ACC TTG GCG ACG ACT → Wait, that’s identical to original? No — look again.

Actually, in the image, under “Mutated DNA sequence #1”, it says:

> TAC ACC TTG GCG ACG ACT

Wait — that can’t be right. Let me check the image description from user input.

Actually, re-reading the user’s text:

In the first box (“Original DNA sequence #1”) it’s:

TAC ACC TTG GCG ACG ACT

Then under “Mutated DNA sequence #1” it shows:

TAC ACC TTG GCG ACG ACT — same? That doesn’t make sense.

Wait — no! Looking carefully at the green boxes in the image (which I can’t see, but based on standard worksheets), usually the mutations are shown with changed bases.

But since the user pasted text, let me read again:

User wrote:

> Original DNA sequence #1
> TAC ACC TTG GCG ACG ACT

> Mutated DNA sequence #1
> TAC ACC TTG GCG ACG ACT ← same? That must be a typo or misread.

Wait — perhaps in the actual image, some letters are crossed out or highlighted. Since I don’t have visual access, I’ll rely on common patterns.

Alternatively, maybe the user meant to show differences.

Looking back at the user's message:

They wrote:

“Mutated DNA sequence #1
TAC ACC TTG GCG ACG ACT”

Same as original? That can't be.

Wait — perhaps there’s a formatting issue. Let me assume that in the real worksheet, the mutated sequences have one or more bases changed, and the green boxes indicate where.

Since this is a practice worksheet, and typically these involve point mutations or insertions/deletions, let’s consider common examples.

But to proceed accurately, I need to infer from context.

Wait — in the third section, “Mutated DNA sequence #3”, it says:

> TAC CCC CTT GGC GAC GAC T

Ah! So probably:

- Original: TAC ACC TTG GCG ACG ACT
- Mutant #1: ??? (maybe one base changed)
- Mutant #2: ???
- Mutant #3: TAC CCC CTT GGC GAC GAC T

But without seeing the exact changes, I can’t proceed unless I make assumptions.

Wait — perhaps the user intended to provide the full data, but due to copy-paste, the mutations aren’t visible.

Alternative approach: Maybe the green boxes in the image highlight the mutated bases, and the student is to figure out the effect.

Since I can’t see the image, I will use a standard example often used in such worksheets.

Common example:

Original DNA: TAC ACC TTG GCG ACG ACT
mRNA: AUG UGG AAC CGC UGC UGA
Protein: Met-Trp-Asn-Arg-Cys-Stop

Mutation 1: Change one base — e.g., change TTG to TTA → still codes for Leu? Wait, TTG is Leu, TTA is also Leu → silent mutation.

But let’s pick a realistic set.

Perhaps:

Mutant #1: TAC ACC TTA GCG ACG ACT → changed TTG to TTA

mRNA: AUG UGG AAU CGC UGC UGA → AAU is Asn (same as AAC) → silent mutation.

Mutant #2: TAC ACC TTG GCA ACG ACT → changed GCG to GCA → both code for Ala? Wait, GCG is Arg, GCA is Ala → missense.

Wait, let’s use codon table properly.

Standard genetic code:

DNA triplet → mRNA codon → amino acid

For template strand DNA, mRNA is complementary.

So for DNA template "TTG" → mRNA "AAC" → Asn

If DNA mutates to "TTA" → mRNA "AAU" → still Asn → silent.

If DNA mutates to "TCG" → mRNA "AGC" → Ser → missense.

Another common mutation: insertion or deletion causing frameshift.

For example, Mutant #3: TAC CCC CTT GGC GAC GAC T — this has an extra base? Let’s count.

Original: TAC ACC TTG GCG ACG ACT → 6 triplets = 18 bases

Mutant #3: TAC CCC CTT GGC GAC GAC T → let’s write it:

TAC CCC CTT GGC GAC GAC T → that’s 7 groups? TAC, CCC, CTT, GGC, GAC, GAC, T → last is single T → so 19 bases → insertion of one base → frameshift.

Yes! That makes sense.

So likely:

- Mutant #1: point mutation (substitution) — silent or missense
- Mutant #2: another substitution — perhaps nonsense
- Mutant #3: insertion → frameshift

But to give accurate answers, I need the exact mutated sequences.

Since the user provided:

> Mutated DNA sequence #1
> TAC ACC TTG GCG ACG ACT ← same as original? Probably not.

Wait — perhaps in the image, the first mutant has a change like:

TAC ACC CTG GCG ACG ACT (changed TTG to CTG)

Then mRNA would be: AUG UGG GAC CGC UGC UGA → GAC is Asp, whereas original was AAC (Asn) → missense.

Or perhaps:

Mutant #1: TAC ACC TTG GCA ACG ACT → GCG to GCA → mRNA: CGC to CGU → both Arg → silent.

I think I need to assume standard values.

Let me look for clues in the user's text.

In the "Effect on Protein" column, for Mutant #3, it says "frameshift" and "protein completely different after mutation".

And for Mutant #1, it might be "silent", etc.

Perhaps the intended mutations are:

Assume:

Mutant #1: TAC ACC TTA GCG ACG ACT (TTG → TTA)

DNA: TAC ACC TTA GCG ACG ACT
mRNA: AUG UGG AAU CGC UGC UGA
Amino acids: Met - Trp - Asn - Arg - Cys - Stop → same as original → silent mutation.

Mutant #2: TAC ACC TTG GCA ACG ACT (GCG → GCA)

DNA: TAC ACC TTG GCA ACG ACT
mRNA: AUG UGG AAC CGU UGC UGA
Amino acids: Met - Trp - Asn - Arg - Cys - Stop → CGU is still Arg → silent? But GCA in DNA template gives CGU in mRNA, which is Arg, same as CGC → silent.

Not good.

Make it: TAC ACC TTG TCA ACG ACT (GCG → TCA)

DNA: TAC ACC TTG TCA ACG ACT
mRNA: AUG UGG AAC AGU UGC UGA
AGU is Ser, whereas original was CGC (Arg) → missense.

Better.

Mutant #3: TAC CCC CTT GGC GAC GAC T (insertion of C after first TAC? Or deletion?)

Original: TAC ACC TTG GCG ACG ACT

Mutant #3: TAC CCC CTT GGC GAC GAC T

Compare:

Position: 1-3: TAC vs TAC — same
4-6: ACC vs CCC — changed A to C
7-9: TTG vs CTT — changed T to C, G to T? Not clear.

Count bases:

Original: 18 bases
Mutant #3: TAC CCC CTT GGC GAC GAC T — let's list:

T A C C C C C T T G G C G A C G A C T → that's 19 bases (last T alone) → so insertion of one base somewhere.

Likely, an extra C inserted after position 3 or something.

To simplify, let's define:

Assume Mutant #3 has an insertion of 'C' after the first triplet, making it:

TAC C ACC TTG GCG ACG ACT → but that's not what's written.

The given is: TAC CCC CTT GGC GAC GAC T

So perhaps it's:

Original: TAC | ACC | TTG | GCG | ACG | ACT
Mutant #3: TAC | CCC | CTT | GGC | GAC | GAC | T → so between pos 3 and 4, a 'C' is inserted, shifting everything.

So new reading frame:

After TAC, instead of ACC, it's CCC, then CTT, etc.

So mRNA will be different from second codon onward.

Let's calculate all three with assumed mutations that match typical worksheets.

I recall a common worksheet where:

Original DNA: TAC ACC TTG GCG ACG ACT
Mutant 1: TAC ACC TTA GCG ACG ACT (TTG->TTA) → silent
Mutant 2: TAC ACC TTG GCA ACG ACT (GCG->GCA) → silent? No, let's make it TAC ACC TTG TGA ACG ACT (GCG->TGA) → TGA in DNA template -> mRNA ACU? Wait.

DNA template TGA -> mRNA ACU -> Thr, but original GCG -> mRNA CGC -> Arg, so missense.

Better to use:

Mutant 2: TAC ACC TTG TAG ACG ACT (GCG->TAG)

DNA TAG -> mRNA AUC -> Ile, while original was Arg -> missense.

Or for nonsense: make it stop codon.

DNA template "ATT" -> mRNA UAA -> stop.

So if mutate GCG to ATT, then mRNA has UAA early.

Let's do that.

Final assumption for accuracy:

Mutant #1: TAC ACC TTA GCG ACG ACT (change TTG to TTA)
Mutant #2: TAC ACC TTG ATT ACG ACT (change GCG to ATT)
Mutant #3: TAC CCC CTT GGC GAC GAC T (insert C after first T, so TAC becomes TACC, but written as TAC CCC... implying insertion after position 3)

For Mutant #3, the sequence is given as "TAC CCC CTT GGC GAC GAC T" — so compared to original "TAC ACC TTG GCG ACG ACT", it seems:

- Position 4: A->C
- Position 5: C->C (same)
- Position 6: C->C (same) — wait, original positions 4-6: ACC, mutant: CCC — so A->C at position 4.

Then positions 7-9: TTG vs CTT — T->C, T->T, G->T? Not consistent.

Perhaps it's a deletion or insertion.

Notice that "TAC CCC CTT GGC GAC GAC T" has 19 characters if we remove spaces: TACCCCTTGGCGACGACT — 18 letters? T-A-C-C-C-C-T-T-G-G-C-G-A-C-G-A-C-T — that's 18 bases? Let's count:

T A C C C C T T G G C G A C G A C T — 18 bases.

Original: T A C A C C T T G G C G A C G A C T — also 18.

So no insertion/deletion? Then why is it different?

Original: TAC ACC TTG GCG ACG ACT
Mutant #3: TAC CCC CTT GGC GAC GAC T

So:

Codon 1: TAC vs TAC — same
Codon 2: ACC vs CCC — A->C
Codon 3: TTG vs CTT — T->C, T->T, G->T? First base T->C, third G->T
Codon 4: GCG vs GGC — C->G
Codon 5: ACG vs GAC — A->G, C->A, G->C? Completely different
Codon 6: ACT vs GAC T — ACT vs GAC, and extra T? "GAC T" suggests GAC and then T, so perhaps codon 6 is GAC and codon 7 is T?? — messy.

Perhaps "GAC GAC T" means two GAC and then T, so 7 codons with last incomplete.

I think there's a mistake in my interpretation.

Another idea: in Mutant #3, the sequence is "TAC CCC CTT GGC GAC GAC T" which is 19 bases if we include the space, but likely it's 18 bases with a shift.

Let's write without spaces:

Original: TACACCTTGGCGACGACT (18 bases)
Mutant #3: TACCCCCTTGGCGACGACT — that's 19 bases? T-A-C-C-C-C-C-T-T-G-G-C-G-A-C-G-A-C-T — 19 bases.

Yes! "TAC CCC CTT GGC GAC GAC T" — if we concatenate: TACCCCTTGGCGACGACT — let's count:

T A C C C C C T T G G C G A C G A C T — positions 1 to 19.

Original is 18 bases, so Mutant #3 has an extra C inserted after position 3.

So insertion of 'C' after the first triplet.

So new sequence: TAC C ACC TTG GCG ACG ACT — but written as TAC CCC CTT GGC GAC GAC T, which matches if we group as TAC, CCC, CTT, GGC, GAC, GAC, T — but the last T is extra, so perhaps it's TAC CCC CTT GGC GAC GAC with T being part of next, but in context, it's 19 bases.

For translation, we start from first base, so with 19 bases, the last codon is incomplete, but we'll translate until stop or end.

So let's define:

Mutant #1: Assume it's TAC ACC TTA GCG ACG ACT (TTG -> TTA)
Mutant #2: Assume it's TAC ACC TTG TAG ACG ACT (GCG -> TAG)
Mutant #3: TAC CCC CTT GGC GAC GAC T (insertion of C after position 3, so sequence is TAC C ACC TTG GCG ACG ACT but written as TACCCCCTTGGCGACGACT)

Now let's calculate each.

---

Mutant #1: TAC ACC TTA GCG ACG ACT

DNA template: TAC ACC TTA GCG ACG ACT
mRNA: AUG UGG AAU CGC UGC UGA
Amino acids: Met - Trp - Asn - Arg - Cys - Stop
Same as original → silent mutation

Type: substitution (point mutation)
Effect: no change in protein

---

Mutant #2: TAC ACC TTG TAG ACG ACT

DNA template: TAC ACC TTG TAG ACG ACT
mRNA: AUG UGG AAC AUC UGC UGA
AUC is Ile, whereas original at that position was CGC (Arg) → so amino acid changed from Arg to Ile → missense mutation

Type: substitution
Effect: one amino acid changed

---

Mutant #3: TAC CCC CTT GGC GAC GAC T (19 bases: TACCCCTTGGCGACGACT)

DNA template: T A C C C C C T T G G C G A C G A C T
Group into codons starting from 1:
1-3: TAC
4-6: CCC
7-9: CTT
10-12: GGC
13-15: GAC
16-18: GAC
19: T (incomplete)

mRNA: complementary, T->A, A->U, C->G, G->C

So:

DNA: TAC -> mRNA: AUG
DNA: CCC -> mRNA: GGG
DNA: CTT -> mRNA: GAA
DNA: GGC -> mRNA: CCG
DNA: GAC -> mRNA: CUG
DNA: GAC -> mRNA: CUG
DNA: T -> mRNA: A (incomplete)

So mRNA: AUG GGG GAA CCG CUG CUG A...

Translate:

AUG = Met
GGG = Gly
GAA = Glu
CCG = Pro
CUG = Leu
CUG = Leu
A... = incomplete, but no stop yet.

Original protein stopped at 6th codon (UGA). Here, we have 6 full codons and one extra base, so protein is longer and completely different sequence after the first amino acid.

Specifically, after Met, it's Gly-Glu-Pro-Leu-Leu-... whereas original was Trp-Asn-Arg-Cys-Stop.

So frameshift mutation due to insertion.

Type: insertion (frameshift)
Effect: protein completely different after mutation, likely nonfunctional

---

Now, to match the worksheet format, we need to fill in for each mutant:

- Mutated DNA sequence (given)
- Transcribed mRNA
- Translated amino acid chain
- Type of mutation
- Effect on protein

Also, for the original, it's already done.

So for Final Answer, since the user wants the solution, I'll provide the filled-in parts for the three mutants.

But the worksheet has columns for each.

Perhaps the final answer should be the completed table entries.

Since the user said "solve the problem accurately", and the problem is to fill in the blanks for the three mutants, I'll provide the answers for each.

Let's summarize:

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Mutant #1:

- Mutated DNA: TAC ACC TTA GCG ACG ACT (assumed)
- mRNA: AUG UGG AAU CGC UGC UGA
- Amino acids: Met - Trp - Asn - Arg - Cys - Stop
- Type of mutation: Substitution (point mutation)
- Effect on protein: Silent mutation (no change)

Mutant #2:

- Mutated DNA: TAC ACC TTG TAG ACG ACT (assumed)
- mRNA: AUG UGG AAC AUC UGC UGA
- Amino acids: Met - Trp - Asn - Ile - Cys - Stop
- Type of mutation: Substitution (point mutation)
- Effect on protein: Missense mutation (one amino acid changed)

Mutant #3:

- Mutated DNA: TAC CCC CTT GGC GAC GAC T (19 bases)
- mRNA: AUG GGG GAA CCG CUG CUG A...
- Amino acids: Met - Gly - Glu - Pro - Leu - Leu - ... (continues until stop or end)
- Type of mutation: Insertion (frameshift)
- Effect on protein: Frameshift mutation; protein sequence completely different after first amino acid, likely nonfunctional

---

But to be precise, for Mutant #3, the amino acid chain should be listed as far as possible.

Since there's no stop codon in the first 6 codons, and the 7th is incomplete, we can say the protein is extended and altered.

In many worksheets, they might write the amino acids until a stop or until the end.

Here, no stop in the sequence given, so perhaps up to the last complete codon.

mRNA has 19 bases, so 6 full codons and 1 extra base.

Codons 1-6: AUG, GGG, GAA, CCG, CUG, CUG → Met, Gly, Glu, Pro, Leu, Leu

Then A... — no amino acid for incomplete codon.

So amino acid chain: Met - Gly - Glu - Pro - Leu - Leu

Whereas original was Met - Trp - Asn - Arg - Cys - Stop

So yes, completely different.

Now, for the final answer, since the user may expect the filled-in values, and given that the options are false, I should just provide the final correct answers for the blanks.

But the instruction is to provide only the final correct answer after reasoning.

Perhaps the final answer is the completed information for the three mutants.

Since it's a worksheet, maybe list the key points.

I think for clarity, I'll box the essential answers.

Final Answer:

For Mutant #1:
- mRNA: AUG UGG AAU CGC UGC UGA
- Amino acids: Met-Trp-Asn-Arg-Cys-Stop
- Mutation type: Substitution
- Effect: Silent

For Mutant #2:
- mRNA: AUG UGG AAC AUC UGC UGA
- Amino acids: Met-Trp-Asn-Ile-Cys-Stop
- Mutation type: Substitution
- Effect: Missense

For Mutant #3:
- mRNA: AUG GGG GAA CCG CUG CUG A...
- Amino acids: Met-Gly-Glu-Pro-Leu-Leu
- Mutation type: Insertion (frameshift)
- Effect: Frameshift; protein completely different after first amino acid

Note: The exact mutated DNA sequences were assumed based on common educational examples since the image details were not fully specified in text. In a real scenario, the specific base changes would be given in the image.